Burner assembly



Nbv. 4, 1969 2 Sheets-Sheet 1 Filed July 26, 1967 s F; W mwiw w m M W W4. 4 E @Wiw m WWM F D MW m 2 m F Nov. 4, 1969 D. A. PIPES ETAL 3,476,491

I BURNER ASSEMBLY Filed July 26, 1967 2 Sheets-Sheet 2 INV NTORS. DENNISA. was

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Patented Nov. 4, 1969 U.S. Cl. 431-46 16 Claims ABSTRACT OF THEDISCLOSURE The disclosure relates to a burner assembly which may be usedas a thermal probe and a pilot burner with a 100% fuel shut-01f. Ahousing supports a switch and a pilot valve and a temperature responsiveactuator is provided for both the switch and the pilot valve. Thehousing also supports a tubular burner with the pilot valve supplyinggaseous fuel thereto. An ignition coil is energized to heat thetemperature responsive actuator and cause the pilot valve to be opened.This permits gas to escape and a pilot flame is ignited by the ignitioncoil. The pilot flame thereupon continues the heating of the temperatureresponsive actuator to maintain the pilot valve actuated and also toactuate the switch which de-energizes the ignition coil and at the sametime electrically energizes the actuation of a main burner valve tocause gas from a main burner to be ignited by the pilot flame. Uponaccidental flame failure, the pilot valve is rapidly closed by thetemperature responsive actuator and also the switch is moved to theopposite condition to close the main burner valve for a 100% fuelshut-off.

Cross reference to related cases The present invention is an improvementon the Thermal Probe and Pilot Burner, Patent No. 3,311,157, issued Mar.28, 1967 to Charles S. Mertler et al. and assigned to the same assigneeas the present invention.

Background of the invention In gas burners such as used in householdappliances, ranges, water heaters and the like, it is a commonrequirement that these devices be safe in operation. One requirement isthat if the main burner be somehow accidently extinguished, then theflow of gas to such main burner should be cut off. Usually a standingpilot is employed in conjunction with such main burner and currentsafety regulations permit gas to escape from such pilot burner, even ifaccidentally extinguished, because this is a small amount of gas, solong as the appliance is adequately vented. However, other gasappliances which may or may not be adequately vented have more strictsafety regulations whereby 100% gas shut-off is required in the eventthat the main burner and pilot burner are extinguished. This means thatthe small amount of gas escaping from the pilot burner must also be shutoff. This is termed a 100% gas shut-oil type of control. Such controlsystems, which in the past have achieved 100% gas shut oil, have ingeneral been fairly complicated requiring additional control systems,not only the one for the main burner but an additional control for thepilot burner, and the additional cost and complexity have mitigatedagainst the general commercial use of such 100% gas shut off pilotburners.

Also many of the prior art pilot burners would not provide a combinationof both electrical control for an ignition coil or control of anelectrical operator for a main burner valve, plus the ability to actuatea pilot valve automatically in response to the presence or absence ofthe flame for 100% gas shut off.

Accordingly, an object of the invention is to provide a burner assemblywhich obviates the above-mentioned disadvantages.

Another object of the invention is to provide a thermal probe and pilotburner wherein the thermal probe is a temperature responsive actuator tocontrol both a switch and a pilot valve.

Another object of the invention is to provide a pilot burner assemblywhich is small and compact, simple and trouble-free, and simple tomanufacture and operate.

Another object of the invention is to provide a pilot burner assemblyhaving a temperature responsive actuator with first and second legmeans, each with different thermal coefiicients of expansion.

Another object of the invention is to provide a pilot burner assemblywherein the temperature responsive actuator is tubular with one memberinside another to protect the inner member of the temperature responsiveactuator.

Summary of the invention The invention may be incorporated in a burnerassembly comprising, in combination, a housing, a tubular burnerattached to said housing and extending away from said housing, a valvemounted relative to said housing and connected to supply fluid fuel tosaid pilot burner, a switch mounted relative to said housing, saidburner presenting port means spaced from said housing, temperatureresponsive actuator means for said switch and said valve, saidtemperature responsive actuator means including first and second legmeans, said first and second leg means each having first and secondends, said first and second leg means having different thermalcoeflicients of expansion, means mounting said first ends of said firstleg means relative to said housing, means interconnecting said secondends of said leg means, said valve having a valve seat and a cooperatingvalve member, means connecting said second leg means to actuate saidvalve member, and means connecting said second end of said second legmeans to actuate said switch.

Other objects and a fuller understanding of the invention may be had byreferring to the following description and claims, taken in conjunctionwith the accompanying drawings, in which:

Brief description of the drawings FIGURE 1 is a longitudinal sectionalview of the presently-preferred embodiment of the burner assemblyaccording to the present invention;

FIGURE 2 is a top plan view of the assembly of FIG- URE 1;

FIGURE 3 is a left-end elevational view of the assembly;

FIGURE 4 is an enlarged longitudinal sectional view of the pilot valve;

FIGURE 5 is an enlarged fragmentary longitudinal sectional view showingthe switch mechanism;

FIGURE 6 is an enlarged fragmentary perspective view of the switch inthe present assembly;

FIGURE 7 is a right-end elevational view of the assembly to a reducedscale; and

FIGURE 8 is a simplified schematic diagram of a burner ignition circuitin which the present pilot burner assembly is embodied.

Description of the preferred embodiment The figures of the drawing showthe preferred embodiment of the invention, however, numerous changes maybe made as will appear hereinafter. The figures of the drawing show apilot assembly 11 which includes generally a housing 12, a tubularburner .13, a pilot valve 14, a switch 15 and a temperature responsiveactuator means 16. The housing 12 includes a metal plate 18 which is amounting plate on which the other parts are mounted. Also the housing 12includes an insulator housing 19 for the switch 15. This insulatorhousing 19 may be of ceramic material to withstand the high temperaturesto which the pilot assembly may be subjected. The temperature responsiveactuator means 16 is provided to actuate the pilot valve 14 and switch.15. The pilot valve 14 is connected to supply gaseous fuel to thetubular pilot burner 13. The temperature responsive actuator means 16includes first and second leg means 21 and 22, respectively, and each ofthe first and second leg means has first and second ends. The tubularpilot burner 13 is one part of the first leg means 21 and has a firstend 23 fixedly mounted on the housing plate 18. The second end 24 of thepilot burner 13 is fixedly attached to an end plate 25, as by welding.

A valve rod 27 is disposed inside said tubular pilot burner 13 as partof said second leg means 22. The valve rod 27 has a first end 28 whichis a conical valve member to cooperate with a valve seat 29 inside saidtubular burner 13 at the first end 23 thereof. The valve rod 27 has asecond end 30 which is externally threaded to be threaded into internalthreads in the second end of the pilot burner 13. A screwdriver slotpermits adjustment of this valve rod 27 to adjust the position of thevalve member 28 relative to the valve seat 29. The valve rod 27 is ofconsiderably smaller diameter than the inside diameter of the tubularburner 13 to permit gas passage beyond the valve seat 29. Gas flow maythen emit from ignition ports 31 and flame ports 32 on this tubularburner 13. This will establish a pilot flame 33.

The temperature responsive actuator means 16 also includes a switchactuator tube 36 as part of said first leg means 21 and a switchactuator rod 37 loosely disposed inside said tube 36 as a part of saidsecond leg means 22. The switch actuator tube 36 has a first end 38carried in the housing plate 18, as better shown in FIGURE 5. The switchactuator tube 36 has a second end 39 fixedly carried in the end plate25. The interior of this second end 39 is threaded to receive anadjusting screw 40. The second end of the switch actuator rod 37 abutsthis adjusting screw 40 and the first end of the switch actuator rod 37is slidably disposed in the switch housing 19 to actuate the switch 15.

The first and second leg means 21 and 22 have different thermalcoefficients of expansion. In this preferred embodiment the first legmeans 21 has a high positive thermal coefficient of expansion, and thesecond leg means 22 has a low positive coefficient of expansion. Thefirst leg means 21 includes the tubular pilot burner 13 and the switchactuator tube 36, both of which may be made from high expansionstainless steel. The second leg means 22 includes the valve rod 27 andthe switch actuator rod 37. The valve rod 27 may be made from ordinarystainless steel which has a low positive thermal coeflicient ofexpansion, and the switch actuator rod may be made from a ceramicmaterial which has a low positive thermal coefficient of expansion, andalso serves to insulate the switch mechanism from the metal plate 13,which would be ground.

The switch 15 is mounted inside the insulated housing 19 on the metalplate 18. This switch 15 has a movable blade 43 carrying movablecontracts on each side of the free end thereof. The movable blade 43 ismounted by a rivet 44 to a terminal 45. The movable blade 43 is normallybiased to push against the switch actuator rod 37, but in the cold orroom temperature position of the pilot assembly 11, the movable blade 43is urged to the left as viewed in FIGURES 1 and so that the movableblade 43 is in contact with a fixed contact 46 which is mounted by arivet 47 to support arm 48. This support arm 48 carries one end of anignition coil 49 which extends in fuel-igniting relationship to theignition ports 31 of the tubular burner 13. The other end of thisignition coil 49 is electrically connected to and supported on a supportarm 50 which is connected to a terminal 51.

The switch actuator rod 37 engages a projection 52 on the movable blade43. When permitted by the expansion of the tubular burner 13, theinherent bias of the movable blade 43 will move the switch actuator rod37 to the right as viewed in FIGURES 1 and 5, that is, toward the endplate 25 and this will permit the movable contacts of the movable blade43 to engage a second fixed contact 54. The fixed contact 54 is mountedby a rivet 55 to a terminal 56. A protective metal shield 58 is fastenedat only one end near the second end of the tubular burner 13, as bywelding, and abuts the bottom of the housing plate 18, to providephysical protection for the ignition coil 49. An insulator 59 is carriedby this metal shield 58 to give physical support to and electricallyinsulate this ignition coil 49.

The FIGURE 8 shows one typical application of many in which this pilotassembly 11 may be used. This FIG- URE 8 is a schematic diamgram of anoven burner circuit showing only a broil burner 61, however, the burner61 shown may be a bake burner or there may be both broil and bakeburners in a double-burner oven. The movable blade 43 is connectedthrough terminal 45, a conductor 62, a manual switch 63, to a lower endof a secondary winding 64 of a step-down transformer 65, the primaryWinding 66 thereof being connected through a switch 67 across aconventional volt power source 68. In one practical embodiment, thesecondary voltage of the transformer 65 may be 12 volts.

The upper end of the transformer secondary winding 64 is connectedthrough a clock switch 69, an oven thermostat switch 70, and a conductor71 to the terminal 51. The oven thermostat switch 70 is also connectedthrough a conductor 72 to an operating coil 73 of an electricaloperating device to actuate a main gas valve 74. The other end of theoperating coil 73 is connected by a conductor 75 to the terminal 56. Themain gas valve 74 is connected in the gas supply line to the main burner61. A manually operable main shut-off valve 76 is connected between agas inlet manifold 77 and the electrically operated main burner valve74.

The switch 63 is under the control of a manually operable control knob78. The control knob 78 is also arranged to operate the switch 67 and tooperate a pilot burner valve 79 connected to control the flow of gasfrom the inlet side of the main shut-off valve 74 to the pilot assembly11.

Operation The pilot assembly 11 may be used with a gaseous fuel tocontrol the pilot flame 33 by controlling the pilot valve 14 as a partof the pilot assembly. Also, the switch 15 is controlled by thetemperature responsive actuator means 16 to control energization of theignition coil 49 which ignites the pilot flame 33 and also controlsenergization of the operating coil 73 which controls the main gas valve74 to control gas flow to the main burner 61. When gas is emitted fromthe main burner 61 it will be ignited by the pilot flame 33. Uponextinguishment of the flame, the temperature responsive actuator means16 controls the pilot valve 14 to close same and also controls theswitch 15 to de-energize the operating coil 73 and hence close the maingas valve 74.

FIGURES 1 and 5 show the pilot assembly 11 in the normal or roomtemperature position, in which case the movable blade 43 is inengagement With the first fixed contact 46. When it is desired to lightthe main burner 61, the manual control knob 78 is moved to permit gasflow through the pilot burner valve 79 to the pilot assembly 11. At thesame time, movement of the control knob 78 energizes the transformer 65through the switch 67 and also the manual switch 63 is closed to permitenergization from the secondary 64 to the ignition coil 49. Theenergization circuit of the ignition coil 49 is from the bottom of thesecondary winding 64, through manual switch 63, conductor .62, terminal45, movable blade 43, fixed contact 46, support arm 48, ignition coil49, support arm 50, terminal 51, conductor 71, oven thermostat switch70, clock switch 69, and return to the upper end of the secondary 64.The ignition coil 49. is thereupon heated to impart heat to thetemperature responsive actuator means 16. The tubular pilot burner 13 isa part of the first leg means of this temperature responsive actuator 16and accordingly since it has a high co-eflicient of expansion this pilotburner 13 will expand away from the housing 12. The inner valve rod 27has a low coefficient of expansion and accordingly it will also move tothe right to open the pilot valve 14. Gas will thereupon flow throughthe pilot conduit 80 into the tubular pilot burner 13 and out throughthe ignition ports 31 and flame ports 32. Gas emitting from the ignitionports 31 will be ignited by the ignition coil 49 and this will establishthe pilot flame 33, primarily from the flame ports 32.

The heat from the pilot flame 33 will envelope both the tubular pilotburner 13 and the switch actuator tube 36 to heat both of these tubes.This pilot flame 33 will therefore maintain the tubular pilot burner 13heated and elongated to maintainthe pilot valve 14 in the opencondition. The heat from the pilot flame 33 will also heat the switchactuator 36 tube which is a part of the first leg means 21 of thetemperature responsive actuator 16. Because of the high thermalcoeflicient of the switch actuator tube 36, it will expand to the right,as viewed in FIG- URE 1, and the inherent bias of the movable blade 43will move the switch actuator rod 37 to the right, permitting themovable blade 43 to move away from the fixed contact 46 into engagementwith the fixed contact 54. This will de-energize the ignition coil 49,which is no longer needed because the pilot flame 33 is alreadyestablished. Engagement of the movable blade 43 with the fixed contact54 will now energize the operating coil 73 of the main gas valve 74.This energization circuit is from the lower end of the secondary 64,through the manual switch 63, conductor 62, terminal 45, movable blade43, fixed contact 54, terminal 56, conductor 75, operating coil 73,oventhermostat switch 70, clock switch 69, and return to the secondarywinding 64. Energization of this operating coil 73 will open the maingas valve 74 and the gas emitting from the main burner 61 will beignited by the pilot flame 33.

The main burner 61 may be turned olf simply by turning the manualcontrol knob 78 to the off position which will de-energize theelectrical circuit and hence de-energize the operating coil 73. Thisshuts off the main gas valve 74. Pilot gas will continue to be emittedfrom the tubular pilot burner 13 until it cools sufliciently that thepilot burner 13 contracts and closes the pilot valve 14. This will takeonly a matter of seconds in a typical application.

Upon accidental flame failure, as by a sudden gust of wind, whichextinguishes both the main burner and the pilot flame, the temperatureresponsive actuator 16 will cool to gradually close the pilot valve 14.At the same time the switch actuator tube 36 will gradually cool andcontract to move the movable blade 43 away from fixed contact 54. Thiswill de-energize the operating coil 73 and accordingly stop gas emissionfrom the main burner 61. When the movable blade 43 of the switch engagesthe fixed contact 46, the ignition coil 49 will again be energized toheat the temperature responsive actuator means 16. This will again setin motion the cycle of events set forth above to rekindle the pilotflame and later the main burner 61.

The end plate 25 inter-engaging the second ends of the tubular pilot 13and the switch actuator tube 36 will help establish that both thetubular burner 13 and tube 36 expand together with heat. Both of thesetubes may be made from the same material so that they will inherentlyexpand together with the same temperature rise. The fact that the firstleg means 21, including pilot burner 13 and switch actuator tube 36,surround and encase the second leg mens 22, including valve rod 27 andswitch actuator rod 37, gives protection to these inner rods to make thedevice compact and yet rugged. The fact that the first and second legmeans 21 and 22 include a rod Within a tube means that both parts of thetemperature responsive actuator 16 are established at approximately thesame temperature when operating at a stable operating condition in thepilot flame 33.

The pilot assembly 11 may be used with two burners 61, for example, onepilot assembly for each burner. In such case the main gas valve 74 maybe a three-way valve with another outlet to a second main burner. Alsoin such case the pilot burner valve 79 could be a three-way valve andthe manual switch 63 a three-way switch. Turning the manual control knob78 in the appropriate direction would cause either the main burner 61 orthe second main burner to be ignited. Because the pilot assembly 11achieves a gas shutoff, namely, a shutoff of not only the main gas flowfrom burner 61 but also the gas flow from the tubular burner 13, it ispossible to eliminate the pilot burner valve 79 where only a singlepilot assembly 11 is being used, however it is shown here forcompleteness.

The first and second leg means 21 and 22 are interconnected by thethreads at the second end of the valve rod 27. This assures that thecombination of movements of the first and second leg means will actuatethe pilot valve 14. Also the first and second leg means 21 and 22 areinterconnected for actuation by the threads at the adjusting screw 40and the second end of the switch actuator tube 36. The switch actuatorrod 37 abuts this adjusting screw 40 and also abuts the movable blade 43at the projection 52 in order to cause actuation of this switch 15 bythe combination of movements of the first and second leg means 21 and22.

Although this invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made only by way of exampleand that numerous changes in the details of the circuit and thecombination and arrangement of circuit elements may be resorted towithout departing from the spirit and scope of the invention ashereinafter claimed.

What is claimed is:

1. A burner assembly comprising, in combination, a housing,

a tubular burner attached to said housing and extending away from saidhousing,

a valve attached to said housing and connected to supply fluid fuel tosaid burner,

a switch attached to said housing,

said burner presenting port means spaced from said housing,

temperature responsive actuator means for said switch and said valve,

said burner port means being directed toward said temperature responsiveactuator means,

said temperature responsive actuator means including first and secondleg means,

said first and second leg means each having first and second ends,

said first and second leg means having different thermal coeflicients ofexpansion,

means mounting said first end of said first leg means on said housing,

means interconnecting said second ends of said leg means,

said valve having a valve seat and a cooperating valve member,

means connecting said second leg means to actuate said valve member,

means connecting said second end of said second leg means to actuatesaid switch,

and heating of said tubular burner effecting opening of said valve topermit emission of fluid fuel to be ignited and the flame thereoffurther heating said temperature responsive actuator means.

2. A burner assembly as set forth in claim 1 wherein said first legmeans has a high positive temperature coeflicient of expansion and saidsecond leg means has a low positive temperature coeflicient ofexpansion.

3. A burner assembly as set forth in claim 1, wherein said vlave seat isnear said housing,

and means to actuate said valve member from said first end of saidsecond leg means.

4. A burner assembly as set forth in claim 1 wherein said valve seat isclosely adjacent said first end of said tubular burner,

an inner rod inside said tubular burner as part of said second legmeans,

and said cooperating valve member is coaxially connected on said firstend of said inner rod.

5. A burner assembly as set forth in claim 1 wherein said first legmeans includes said tubular burner and a switch actuator tube,

said second leg means includes a valve rod as an inner rod inside saidtubular burner and includes a switch actuator rod inside said switchactuator tube,

and an end plate interconnecting said second ends of said tubular burnerand said switch actuator tube.

6. A burner assembly as set forth in claim 5 wherein said tubular burnerand said switch actuator tube have a high positive temperaturecoeflicient of expansion,

said valve rod is metallic and has a low positive temperaturecoeflicient of expansion,

and said switch actuator rod is ceramic and has a low positivetemperature coefiicient of expansion.

7. A burner assembly as set forth in claim 5 including threaded meansinterconnecting the second ends of said valve rod and said tubularburner,

a threaded adjusting screw at said second end of said switch actuatortube,

and the second end of said switch actuator rod bearing against saidadjusting screw.

8. A burner assembly as set forth in claim 1 including an inner rodinside said tubular burner as part of said second leg means, and whereinsaid tubular burner expands upon being heated to move said inner rod andmove said valve member away from said valve seat to permit emission offluid fuel which will ignite and the flame therefrom will maintain saidtubular burner heated and expanded to maintain said valve open.

9. A burner assembly as set forth in claim 1 wherein said burner flameheats said first leg means to act through said second leg means foractuation of said switch to an alternate switch condition,

a main gas valve,

and means controlled by actuation of said switch to energize said maingas valve.

A burner assembly as set forth in claim 1 including an ignition coilextending in igniting relation to the port means of said tubular burner,

and means controlling energization of said ignition coil through saidswitch.

11. A burner assembly as set forth in claim 1 wherein said switchactuator means includes a switch actuator tube as part of said first legmeans and includes a switch actuator rod as part of said second legmeans,

said second ends of said switch actuator rod and tube beinginterconnected,

and said first end of said switch actuator rod being slidably disposedinside said first end of said switch actuator tube and disposed toactuate said switch.

12. A burner assembly as set forth in claim 1 wherein said first legmeans is tubular and said second leg means is disposed inside saidtubular first leg means.

13. A burner assembly as set forth in claim 1 wherein said first andsecond leg means are established at substantially the same temperatureunder stable conditions of operation in the flame from said port meansof said tubular burner.

14. A burner assembly as set forth in claim 1 wherein said first legmeans includes said tubular burner and a switch actuator tube,

said second leg means includes an inner rod inside each of said tubularburner and said -switch actuator tube,

said tubular burner and said valve rod having different thermalcoefficients of expansion to actuate said valve between open and closedpositions upon the presence and absence of a burner flame,

and said switch actuator 'tube and rodhaving different thermalcoeflicient s of expansion to actuate said switch between first andsecond conditions upon the presence and absence of a burner flame.

15. A- burner assembly as set forth in claim 14 wherein said tubularburner and switch actuator tube having high positive temperaturecoefficients of expansion and said valve rod and switch actuator rod"have low positive coefficients of expansion.

16. A burner assembly as set forth'in claim 1 including an ignition coilextending in igniting relation to the tubu lar burner,

said switch actuator means including a switch actuator tube and a switchactuator 'r'od slidably disposed therein and each having first andsecond ends,

said tubular burner and said switch actuator tube constituting saidfirst leg means,

an inner valve rod inside said tubular burner,

said valve rod and said switch actuator rod constituting said second legmeans,

an end plate fixedly attached to the second ends of said tubular burnerand said switch actuator tube, threaded means interconnecting saidsecond ends of said valve rod and said tubular burn er,

an adjusting screw threadably inserted in said second end of said switchactuator tube, said switch actuator rod acting between said adjustingscrew and said switch,

said tubular burner and said switch actuator tube having a high positivetemperature coefficient of expansion,

said valve rod having a low positive temperature coefficient ofexpansion,

said switch actuator rod being ceramic with a low positive temperaturecoefficient of expansion,

a main burner valve,

means connecting said switch to establish actuation of said main burnervalve,

and circuit means interconnecting said ignition coil and said switchwhereby heating of said tubular burner by energization of said ignitioncoil through said switch causes elongation of said tubular burner toopen said first mentioned valve and the emission of gaseous fueltherefrom is ignited by the ignition coil and the burner flame therefrommaintains said tubular burner elongated, and whereby the burner flameheats the switch actuator tube to expand same and actuate said switch tode-energii'e said coil'and actuate said main burner valve.

References Cited Mertler et al. 43 l-46 EDWARD G. FAVORS, PrimaryExaminer

